Audio Database

PMA-500
Commentary

This is a pre-main amplifier developed by DENON in pursuit of musical quality by investing the experience and technology of professional equipment.

The power amplifier uses a PNP-NPN pair of Darlington power transistors manufactured by Motorola Inc. of the United States. The circuit configuration consists of a PNP-NPN Darlington power transistor with excellent symmetry in electrical characteristics and an all-stage direct connection OCL circuit. This realizes low distortion.
In addition, a Darlington transistor with Tj of 55 to 200 ° C and collector loss of 150W is used, heat radiation effect and stability of temperature compensation of bias circuit are taken into consideration. Thus, a safe operating area (ASO) is considered in the design and stable operation is achieved.

The power supply section is equipped with a non-inductive high-ripple type chemical capacitor and a power transformer that reduces internal resistance to suppress temperature rise and takes into consideration the effects of leakage flux from the material aspect.

The preamplifier section is composed of a direct-coupled circuit of a high-voltage low-noise transistor and is structured in consideration of various characteristics.
In addition, the power supply unit is used as a stabilizing power supply to stabilize the operation, and an emitter-follower buffer amplifier is used at every important point.

It has two microphone input terminals, each equipped with a dedicated microphone amplifier and a full-scale balanced 2-channel microphone mixing circuit with a level adjustment volume.

Equipped with 3-step switching type muting switch.

Equipped with a standard Octar socket for MC matching switch and MM/MC change-over switch.
The socket section is designed to move the MC transformer in the front-back direction and the rotational direction so that it is not affected by the guide hum. All general Octar pin type devices are interchangeable.

It is equipped with functions such as low filter and high filter, tone defeat switch and loudness.

Model Rating
Type All-silicon transistor stereo premain amplifier
Power Amplifier Unit
Music output 100W
Rated output
When one channel is driven : 42Wx2 (8 Ω, THD 0.1%)
When both channels are driven : 40W + 40W (8 Ω, THD0. 5%)
37W + 37W (8 Ω, THD 0.1%)
Harmonic distortion factor 0.03% or less (at -3dB rated output)
Intermodulation distortion factor (60 hz : 7 khz = 4 : 1) 0.06% or Less (at -3dB Rated Output)
Output bandwidth 5 Hz ~ 35 kHz + 0 -1dB (THD 0.1%)
5 hz or Less ~ 75 khz + 0 -3dB (THD 0.5%)
Frequency Response (Output Po = 10 Wconst.) 10 Hz to 100 kHz + 0 -1dB
Input impedance 80k Ω ± 20% (5 Hz or less to 20 kHz or more)
Input sensitivity 1Vrms/100k Ω
Residual noise 0.01 μ W or less (input terminal short circuit)
Signal-to-noise ratio 95 dB or more
Damping factor 50 or More (5 Hz or Less to 10 kHz)
Output impedance 0.16 Ω or Less (Pure Resistance at 1 kHz or Less)
Preamplifier Section
Rated output 1.0Vrms
Maximum power output 5.0Vrms
Harmonic distortion factor Maximum output : 0.1% or less (100 Hz, 1 kHz, 10 kHz)
Rated output : 0.05% or less (100 Hz, 1 kHz, 10 kHz)
Cross modulation distortion factor 0.1% or Less (at Rated Output)
Frequency Response (Tone Defeat) 10 Hz ~ 40 kHz + 0 -1dB
Input Sensitivity / Impedance Phono1, 2 : 2mVrms/60k Ω ± 20%
MIC : 1mVrms/100k Ω ± 20%
Tuner, AUX1, 2 : 100mVrms/60k Ω ± 20%
Tape PB : 500mVrms/100k Ω ± 20%
Maximum Allowable Input (THD 1% or less) Phono1, 2 : 200 mVrms (1 kHz)
MIC L/R:80mVrms
RIAA deviation 30 Hz to 15 kHz ± 0.5 dB
S/N ratio (input terminal short-circuit) Phono1, 2 : 65 dB or more
MIC : 55 dB or more
Tuner, AUX1, 2, Tape : 75 dB or more
Audio Muting 0, -10dB, -20dB
Tone control Bass : + 10 dB ~ -10.5 dB (80 Hz)
Treble : + 10 dB ~ -9dB (12 kHz)
High Filter 9 kHz, 12dB/oct.
Low Filter 40 Hz, 12dB/oct.
Output Level / Impedance Tape rec (DIN) : 100mVrms/1k Ω or less (40mVrms/80k Ω)
<General>
Semiconductor used Transistor : 39
FET : 2
Diode : 10 pcs
Varistor : 2 pieces
AC outlet Switched : 2 systems, 250W
Unswitched : 1 line, 150W
Power supply voltage 100 VAC / 120 V / 200 V / 220 V / 240 V, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law) 56W
External dimensions Width 430x Height 140x Depth 350 mm
Weight 12.5kg